About 6 months ago I bought a Weaver model 800362 Tactical scope ($768) for my AR10. I chose a Weaver because I’ve had one (4x, came with the rifle acquired in 1964) and it still works fine.
Mounted the Weaver and went to the range to zero the rifle. The best 3 round shot group I could achieve was 3” (most around 5”) at 100 yards. Now the AR10 has a reputation of being better than that, so I bought a bench rest and tried again with the same results. So figured it must be me just getting older. BUT maybe it was the rifle (hard to admit your eyes are going), so I ordered a Springfield .308 to try.
While waiting for the Springfield to arrive one day, at Sportsman’s Warehouse, I was whining to one of the salesman about the AR10 and got talked into trying a Vortex scope ($752). I mounted it on my AR10, and headed for the range. The rifle with a Vortex scope shot sub-MOA groups at 100 yards and 1.5” to 2” groups at 200 yards for about 48 rounds. (I was ecstatic, my eyesight had improved
) I was having so much fun I couldn’t stop shooting. A local guy on the next lane asked if he could try the AR10 (with his ammo, different than mine) and shot slightly better than I was doing. He kept badgering me to sell him the rifle until I finally sold it to him for about $400 more than I had in the gun. (After all, my eyes were getting better and I had a new rifle on the way
).
I picked up the Springfield and stopped by the range (without mounting the Weaver scope because the range was on the way back to my house). The Springfield (with iron sights) shot a .8” group at 100 yds after shooting 9 lapping rds and cleaning the barrel and zeroing . WOW, just wait until I get the scope on this rifle (my eyes are getting better every time I go to the range, but I was having to use those bright red sticker for the bulls eye at 100 yds). Well winter set in and in Mississippi that means rain and cold and no range days without slogging through the mud down range to check/change your target. So I put a Troy chases, Troy flip-up iron sights, Magpol stock, a bipod and the Weaver scope on the Springfield, while waiting for a dry range.
Last Saturday I headed out to zero and have some fun. My cold (first) shot was about 4” low @ 7 o‘clock (to be expected), the next 2 shots were dead on the vertical target line, 6” low. OK move to 100 yds, adjust and shoot 3 rds.
Those 3 were a 1” group @ 11 o’clock about 2.5” off center. Maybe I screwed up the adjustment, so adjust for elevation, one more shot, 9 o’clock 1” off center, good (now lets have some fun). New target, adjust windage 1” to the right and fire 3 rds. #1) 8 o’clock 5” off center, #2) 7 o’clock 7” off center, #3) completely off the paper. ***
Check the scope rings, their still tight. Ammo out of the same box of 20 I used with the iron sights 2 months ago. Must be the Troy build I did. Pull the scope off the gun. Zero the Troy flip-up sights. And move target back to 100 yds (with bright red sticker for bulls eye). Three rds. Half inch group @ 4 o’clock 3” off center, adjust and shoot 3 rds. 8th group on 1.5” red sticker.
Conclusion, rifle is good to go, Troy build is good to go, Weaver scope is junk?
WHAT AM I MISSING HERE? 
I’ve called Weaver’s Technical Service Department, spoke to an automated answering machine, no return call yet. Emailed Weaver’s Customer Service Department, no return email yet.
I would like in put from you guys, WHAT am I missing?